@kierwinyoung: Start charging them for your art! If you keep taking free requests, they'll start to think you're there for them. If you don't want to draw their request, just say no and tell them you're too busy to work on requests.
@n33d2skate: Yeah, I should just refuse them, though. I never been the one charging them. I just charge people who're not in the Internet. like my Friends in my Place. Although I thought about charging them in Deviantart, I just don't know how. So yeah probably should just say no.
Although one of my is that, I'm quite having a hard time to say "No" people. I kinda think it's rude or not nice, if I refuse. then I'd be a sucker if I accept. this was been a long problem of mine though.